Dual mode relaxation oscillator generating a clock signal operating at a frequency substantially same in both first and second power modes
First Claim
1. An oscillator circuit comprising:
- a relaxation oscillator circuit;
a first current source for establishing a first reference voltage for use in causing said relaxation oscillator circuit to operate in a first power mode to generate a clock of a first accuracy;
a second current source for establishing a second reference voltage for use in causing said relaxation oscillator circuit to operate in a second power mode to generate a clock of a second accuracy, wherein said first current source is not operable to establish said second reference voltage; and
a control coupled to said first current source and said second current source for switching between said first power mode and said second power mode, wherein said relaxation oscillator circuit generates a clock signal operating at a frequency that is substantially the same in both said first power mode and said second power mode.
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Accused Products
Abstract
A microcontroller having a dual mode relax oscillator that is trimmable. In one embodiment, the present invention provides a relaxation oscillator circuit comprising two current sources for establishing a reference voltage for use in causing the relaxation oscillator circuit to operate in two power modes, and a control coupled to both current sources for switching between power modes. In one embodiment, one power mode is a low power mode for standard operation of the microcontroller and one power mode is a very low power mode for use in a sleep mode. In one embodiment, the relaxation oscillator circuit further comprises digitally trimmable components operable to control a current charging a capacitor of the relaxation oscillator circuit to account for process variation in the capacitor, wherein the current is for controlling a frequency of the microcontroller.
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Citations
26 Claims
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1. An oscillator circuit comprising:
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a relaxation oscillator circuit; a first current source for establishing a first reference voltage for use in causing said relaxation oscillator circuit to operate in a first power mode to generate a clock of a first accuracy; a second current source for establishing a second reference voltage for use in causing said relaxation oscillator circuit to operate in a second power mode to generate a clock of a second accuracy, wherein said first current source is not operable to establish said second reference voltage; and a control coupled to said first current source and said second current source for switching between said first power mode and said second power mode, wherein said relaxation oscillator circuit generates a clock signal operating at a frequency that is substantially the same in both said first power mode and said second power mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A microcontroller comprising:
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a bus; a processor coupled to said bus; a memory unit coupled to said bus; a plurality of input/output pins; and a timer circuit coupled to said bus for performing a timing function, said timer circuit comprising a relaxation oscillator circuit having a first power mode associated with a first current source and a second power mode associated with a second current source wherein said relaxation oscillator circuit generates a clock signal operating at a frequency that is substantially the same in both said first power mode and said second power mode, said first power mode and said second power mode being switchable under a control, wherein said relaxation oscillator circuit comprises; said first current source coupled to said control for establishing a first reference voltage for use in causing said relaxation oscillator to operate in a first power mode to generate a clock of a first accuracy, wherein said first current source is not used during said second power mode; and said second current source coupled to said control for establishing a second reference voltage for use in causing said relaxation oscillator to operate in a second power mode to generate a clock of a second accuracy. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. In a relaxation oscillator circuit having a first current source for a first power mode and a second current source for a second power mode, a method for generating clock signals comprising:
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selecting a switched current source corresponding to a present power mode by switching between said first current source for said first power mode and said second current source for said second power mode, wherein said first current source is not used during said second power mode; generating a reference voltage based on said switched current source; and in response to said reference voltage, using said relaxation oscillator circuit to generate a clock signal having an accuracy that depends on said present power mode, wherein said clock signal operates at a frequency that is substantially the same in both said first power mode and said second power mode. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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Specification